• Where can one get parts these days?

    From neo5bass@gmail.com@21:1/5 to All on Fri Apr 22 08:02:05 2022
    I suspect if a real source is around, no one wants to tell, but I am having a hard time trying to get simple passive components. Melf resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    Thanks

    Don

    --- SoupGate-Win32 v1.05
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  • From John S@21:1/5 to neo5...@gmail.com on Fri Apr 22 10:04:57 2022
    On 4/22/2022 10:02 AM, neo5...@gmail.com wrote:
    I suspect if a real source is around, no one wants to tell, but I am having a hard time trying to get simple passive components. Melf resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    Thanks

    Don

    Mouser
    Digikey

    If you can't find it in one of those two places, then you don't need it.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to All on Fri Apr 22 08:56:57 2022
    On Fri, 22 Apr 2022 10:04:57 -0500, John S <Sophi.2@invalid.org>
    wrote:

    On 4/22/2022 10:02 AM, neo5...@gmail.com wrote:
    I suspect if a real source is around, no one wants to tell, but I am having a hard time trying to get simple passive components. Melf resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    Thanks

    Don

    Mouser
    Digikey

    If you can't find it in one of those two places, then you don't need it.

    There is a surprising variety of parts from Amazon and even WalMart.



    --

    I yam what I yam - Popeye

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Lasse Langwadt Christensen@21:1/5 to All on Fri Apr 22 09:02:43 2022
    fredag den 22. april 2022 kl. 17.02.10 UTC+2 skrev neo5...@gmail.com:
    I suspect if a real source is around, no one wants to tell, but I am having a hard time trying to get simple passive components. Melf resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    lcsc.com

    --- SoupGate-Win32 v1.05
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  • From John Robertson@21:1/5 to John S on Fri Apr 22 09:16:57 2022
    On 2022/04/22 8:04 a.m., John S wrote:
    On 4/22/2022 10:02 AM, neo5...@gmail.com wrote:
    I suspect if a real source is around, no one wants to tell, but I am
    having a hard time trying to get simple passive components. Melf
    resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    Thanks

    Don

    Mouser
    Digikey

    If you can't find it in one of those two places, then you don't need it.

    Unless you are into restoring classic (pre-1990) equipment that is...

    John :-#)#

    --
    (Please post followups or tech inquiries to the USENET newsgroup)
    John's Jukes Ltd.
    MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
    (604)872-5757 (Pinballs, Jukes, Video Games)
    www.flippers.com
    "Old pinballers never die, they just flip out."

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Klaus Kragelund@21:1/5 to Lasse Langwadt Christensen on Fri Apr 22 23:23:46 2022
    22.04.22 19:02, Lasse Langwadt Christensen wrote:
    fredag den 22. april 2022 kl. 17.02.10 UTC+2 skrev neo5...@gmail.com:
    I suspect if a real source is around, no one wants to tell, but I am having a hard time trying to get simple passive components. Melf resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    lcsc.com
    Schhh. You are destroying the last reserve

    --
    Klaus

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  • From rbowman@21:1/5 to neo5...@gmail.com on Sun Apr 24 20:27:13 2022
    On 04/22/2022 09:02 AM, neo5...@gmail.com wrote:
    I suspect if a real source is around, no one wants to tell, but I am having a hard time trying to get simple passive components. Melf resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    Thanks

    Don

    https://www.newark.com/
    https://www.digikey.com/
    https://www.allelectronics.com/

    You didn't mention where you are. Newark has a UK warehouse but I don't
    know how much they stock. DigiKey runs more toward digital devices as
    you might guess. All Electronics is a bit strange. I think they're the
    OddLots of the electronics world but sometimes you get lucky and find
    something useful at a good price.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From DecadentLinuxUserNumeroUno@decadenc@21:1/5 to rbowman on Mon Apr 25 02:53:52 2022
    rbowman <bowman@montana.com> wrote in
    news:jcmf7vF227cU1@mid.individual.net:

    On 04/22/2022 09:02 AM, neo5...@gmail.com wrote:
    I suspect if a real source is around, no one wants to tell, but I
    am having a hard time trying to get simple passive components.
    Melf resistors, Pulse resistant resistors stuff like that. Are
    there any places selling basic components besides E-Bay?

    Thanks

    Don

    https://www.newark.com/
    https://www.digikey.com/
    https://www.allelectronics.com/

    You didn't mention where you are. Newark has a UK warehouse but I
    don't know how much they stock. DigiKey runs more toward digital
    devices as you might guess. All Electronics is a bit strange. I
    think they're the OddLots of the electronics world but sometimes
    you get lucky and find something useful at a good price.



    "Stackpole" makes hi rel carbon comp resistors with pulse tolerant
    resistive media formulations.

    --- SoupGate-Win32 v1.05
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  • From John Doe@21:1/5 to rbowman on Mon Apr 25 02:32:53 2022
    rbowman wrote:

    https://www.newark.com/
    https://www.digikey.com/
    https://www.allelectronics.com/

    You didn't mention where you are. Newark has a UK warehouse but I don't
    know how much they stock. DigiKey runs more toward digital devices as
    you might guess. All Electronics is a bit strange. I think they're the OddLots of the electronics world but sometimes you get lucky and find something useful at a good price.

    Is Mouser Electronics not in the ballpark?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From rbowman@21:1/5 to DecadentLinuxUserNumeroUno@decadenc on Sun Apr 24 23:49:19 2022
    On 04/24/2022 08:53 PM, DecadentLinuxUserNumeroUno@decadence.org wrote:
    rbowman <bowman@montana.com> wrote in
    news:jcmf7vF227cU1@mid.individual.net:

    On 04/22/2022 09:02 AM, neo5...@gmail.com wrote:
    I suspect if a real source is around, no one wants to tell, but I
    am having a hard time trying to get simple passive components.
    Melf resistors, Pulse resistant resistors stuff like that. Are
    there any places selling basic components besides E-Bay?

    Thanks

    Don

    https://www.newark.com/
    https://www.digikey.com/
    https://www.allelectronics.com/

    You didn't mention where you are. Newark has a UK warehouse but I
    don't know how much they stock. DigiKey runs more toward digital
    devices as you might guess. All Electronics is a bit strange. I
    think they're the OddLots of the electronics world but sometimes
    you get lucky and find something useful at a good price.



    "Stackpole" makes hi rel carbon comp resistors with pulse tolerant
    resistive media formulations.


    Yeah, but the question was where to buy them.

    https://www.arrow.com/en

    Another one I forgot about.

    --- SoupGate-Win32 v1.05
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  • From rbowman@21:1/5 to John Doe on Sun Apr 24 23:45:47 2022
    On 04/24/2022 08:32 PM, John Doe wrote:
    rbowman wrote:

    https://www.newark.com/
    https://www.digikey.com/
    https://www.allelectronics.com/

    You didn't mention where you are. Newark has a UK warehouse but I don't
    know how much they stock. DigiKey runs more toward digital devices as
    you might guess. All Electronics is a bit strange. I think they're the
    OddLots of the electronics world but sometimes you get lucky and find
    something useful at a good price.

    Is Mouser Electronics not in the ballpark?


    Definitely.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to neo5bass@gmail.com on Mon Apr 25 06:58:33 2022
    On Fri, 22 Apr 2022 08:02:05 -0700 (PDT), "neo5...@gmail.com" <neo5bass@gmail.com> wrote:

    I suspect if a real source is around, no one wants to tell, but I am having a hard time trying to get simple passive components. Melf resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    Thanks

    Don

    Why melfs?

    The x-chapters (H+H) have some great data on resistor overload.



    --

    I yam what I yam - Popeye

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Mon Apr 25 18:57:07 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Fri, 22 Apr 2022 10:04:57 -0500, John S <Sophi.2@invalid.org>
    wrote:

    On 4/22/2022 10:02 AM, neo5...@gmail.com wrote:
    I suspect if a real source is around, no one wants to tell, but I am having a hard time trying to get simple passive components. Melf resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    Thanks

    Don

    Mouser
    Digikey

    If you can't find it in one of those two places, then you don't need it.

    There is a surprising variety of parts from Amazon and even WalMart.



    A plug for the metasearch engines: octopart.com, findchips.com,
    oemstrade.com.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Tabby@21:1/5 to jla...@highlandsniptechnology.com on Tue Apr 26 06:12:36 2022
    On Monday, 25 April 2022 at 14:58:45 UTC+1, jla...@highlandsniptechnology.com wrote:
    On Fri, 22 Apr 2022 08:02:05 -0700 (PDT), "neo5...@gmail.com" <neo5...@gmail.com> wrote:

    I suspect if a real source is around, no one wants to tell, but I am having a hard time trying to get simple passive components. Melf resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    Thanks

    Don
    Why melfs?

    The x-chapters (H+H) have some great data on resistor overload.

    always hated how milf resistors roll off the board if not glued.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to All on Tue Apr 26 07:07:38 2022
    On Tue, 26 Apr 2022 06:12:36 -0700 (PDT), Tabby <tabbypurr@gmail.com>
    wrote:

    On Monday, 25 April 2022 at 14:58:45 UTC+1, jla...@highlandsniptechnology.com wrote:
    On Fri, 22 Apr 2022 08:02:05 -0700 (PDT), "neo5...@gmail.com"
    <neo5...@gmail.com> wrote:

    I suspect if a real source is around, no one wants to tell, but I am having a hard time trying to get simple passive components. Melf resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    Thanks

    Don
    Why melfs?

    The x-chapters (H+H) have some great data on resistor overload.

    always hated how milf resistors roll off the board if not glued.

    Pick-and-place machines don't like them either.

    Silly concept.

    Here's an instrument with a strange mix of melfs and normal parts.

    https://www.dropbox.com/sh/zx1zj4a3uxfvw18/AABzb61Kobc0-6NS9Co8MRTXa?dl=0



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
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  • From DecadentLinuxUserNumeroUno@decadenc@21:1/5 to Tabby on Tue Apr 26 20:02:11 2022
    Tabby <tabbypurr@gmail.com> wrote in news:fad3b7e4-fb8b-48e5-909d-0caa638ea577n@googlegroups.com:

    On Monday, 25 April 2022 at 14:58:45 UTC+1,
    jla...@highlandsniptechnology.com wrote:
    On Fri, 22 Apr 2022 08:02:05 -0700 (PDT), "neo5...@gmail.com"
    <neo5...@gmail.com> wrote:

    I suspect if a real source is around, no one wants to tell, but
    I am having a hard time trying to get simple passive components.
    Melf resistors, Pulse resistant resistors stuff like that. Are
    there any places selling basic components besides E-Bay?

    Thanks

    Don
    Why melfs?

    The x-chapters (H+H) have some great data on resistor overload.

    always hated how milf resistors roll off the board if not glued.


    I am sure that even a soldered milf resistor could heat up and
    reflow its solder and get knocked loose too.

    It is easy enough to fashion the leads of an axial leaded carbon
    comp resositor to attach to a pair of SMD pads. I have done so, in
    fact. Even done so with HV feedback resistors Protruding lead ends
    and HV potentials do not always mix well.

    We "bump soldered" a lot of parts in the HV sections of our
    designs. After soldering normally perform quick additions of more
    solder to form a bead of solder at the node. Cannot do it too slow
    or it wicks into the hole just as normal. Makes for a less noisy
    output as well. Corona isn't just a glowing halo.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to DecadentLinuxUserNumeroUno@decadenc on Tue Apr 26 14:13:47 2022
    On Tue, 26 Apr 2022 20:50:58 -0000 (UTC), DecadentLinuxUserNumeroUno@decadence.org wrote:

    jlarkin@highlandsniptechnology.com wrote in >news:cmuf6hl3nff5nmv89ocilj0kdbjnujc8gj@4ax.com:

    Pick-and-place machines don't like them either.

    Depends on the pick head used. D'Oh!

    Silly concept.

    Brainless assessor. Silly assessment. Par for the course for you,
    Johnny.

    Do you design with melfs? Why?


    They were to replicate the design and features of glass encapsulated,
    hermetically sealed components like diodes and such.

    Why?

    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From DecadentLinuxUserNumeroUno@decadenc@21:1/5 to jlarkin@highlandsniptechnology.com on Tue Apr 26 20:50:58 2022
    jlarkin@highlandsniptechnology.com wrote in news:cmuf6hl3nff5nmv89ocilj0kdbjnujc8gj@4ax.com:

    Pick-and-place machines don't like them either.

    Depends on the pick head used. D'Oh!

    Silly concept.

    Brainless assessor. Silly assessment. Par for the course for you,
    Johnny.

    They were to replicate the design and features of glass encapsulated, hermetically sealed components like diodes and such.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From whit3rd@21:1/5 to John Larkin on Thu Apr 28 20:03:56 2022
    On Tuesday, April 26, 2022 at 2:13:58 PM UTC-7, John Larkin wrote:
    On Tue, 26 Apr 2022 20:50:58 -0000 (UTC),
    DecadentLinux...@decadence.org wrote:

    Do you design with melfs? Why?

    They were to replicate the design and features of glass encapsulated,
    hermetically sealed components like diodes and such.

    Why?

    The glass package is thermally better than epoxies (or used to be)
    and extremely well sealed against contaminants. Classic diode test: run
    ten or twenty amps through a 1N4007 until you hear a 'pow' and see smoke.
    Then put it on a curve tracer. It still works normally (underneath the epoxy,
    the package was plug-sealed glass). The epoxy is burnt and cracked, though.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Clive Arthur@21:1/5 to jlarkin@highlandsniptechnology.com on Fri Apr 29 09:54:56 2022
    On 25/04/2022 14:58, jlarkin@highlandsniptechnology.com wrote:
    On Fri, 22 Apr 2022 08:02:05 -0700 (PDT), "neo5...@gmail.com" <neo5bass@gmail.com> wrote:

    I suspect if a real source is around, no one wants to tell, but I am having a hard time trying to get simple passive components. Melf resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    Thanks

    Don

    Why melfs?

    The x-chapters (H+H) have some great data on resistor overload.

    MELFs dissipate more for a given footprint and can take a bigger solder
    fillet which holds them in place better under high vibration,
    particularly when the solder's weakened at high temperatures, and if
    potted, there's more body for the potting to hold.

    They're also much prettier.

    Personally, I find them easier to handle if I have to replace one
    because there's more to grip, but that's a trivial concern.

    But they have been noticeably harder to obtain for a few years.

    Q. Were MELFs originally made that way because they're essentially
    leaded parts without the leads? [It goes full circle - chop open a
    leaded dipped ceramic capacitor and you'll often find inside a surface
    mount part with leads soldered/welded on.]

    --
    Cheers
    Clive

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Clive Arthur on Fri Apr 29 10:17:17 2022
    Clive Arthur wrote:
    On 25/04/2022 14:58, jlarkin@highlandsniptechnology.com wrote:
    On Fri, 22 Apr 2022 08:02:05 -0700 (PDT), "neo5...@gmail.com"
    <neo5bass@gmail.com> wrote:

    I suspect if a real source is around, no one wants to tell, but I am
    having a hard time trying to get simple passive components. Melf
    resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    Thanks

    Don

    Why melfs?

    The x-chapters (H+H) have some great data on resistor overload.

    MELFs dissipate more for a given footprint and can take a bigger solder fillet which holds them in place better under high vibration,
    particularly when the solder's weakened at high temperatures, and if
    potted, there's more body for the potting to hold.

    They're also much prettier.

    Personally, I find them easier to handle if I have to replace one
    because there's more to grip, but that's a trivial concern.

    But they have been noticeably harder to obtain for a few years.

    Q. Were MELFs originally made that way because they're essentially
    leaded parts without the leads?  [It goes full circle - chop open a
    leaded dipped ceramic capacitor and you'll often find inside a surface
    mount part with leads soldered/welded on.]

    Yup. At one point some bright outfit was selling MELFs with square end
    caps to prevent them from rolling around. Dunno if they're still available.

    Cheers

    Phil Hobbs


    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to clive@nowaytoday.co.uk on Fri Apr 29 07:24:43 2022
    On Fri, 29 Apr 2022 09:54:56 +0100, Clive Arthur
    <clive@nowaytoday.co.uk> wrote:

    On 25/04/2022 14:58, jlarkin@highlandsniptechnology.com wrote:
    On Fri, 22 Apr 2022 08:02:05 -0700 (PDT), "neo5...@gmail.com"
    <neo5bass@gmail.com> wrote:

    I suspect if a real source is around, no one wants to tell, but I am having a hard time trying to get simple passive components. Melf resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    Thanks

    Don

    Why melfs?

    The x-chapters (H+H) have some great data on resistor overload.

    MELFs dissipate more for a given footprint and can take a bigger solder >fillet which holds them in place better under high vibration,
    particularly when the solder's weakened at high temperatures, and if
    potted, there's more body for the potting to hold.

    They're also much prettier.

    Personally, I find them easier to handle if I have to replace one
    because there's more to grip, but that's a trivial concern.

    But they have been noticeably harder to obtain for a few years.

    Q. Were MELFs originally made that way because they're essentially
    leaded parts without the leads? [It goes full circle - chop open a
    leaded dipped ceramic capacitor and you'll often find inside a surface
    mount part with leads soldered/welded on.]

    https://i.chzbgr.com/full/6919676928/h2C8459FA/melf



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jlarkin@highlandsniptechnology.com@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Fri Apr 29 07:38:21 2022
    On Fri, 29 Apr 2022 10:17:17 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Clive Arthur wrote:
    On 25/04/2022 14:58, jlarkin@highlandsniptechnology.com wrote:
    On Fri, 22 Apr 2022 08:02:05 -0700 (PDT), "neo5...@gmail.com"
    <neo5bass@gmail.com> wrote:

    I suspect if a real source is around, no one wants to tell, but I am
    having a hard time trying to get simple passive components. Melf
    resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    Thanks

    Don

    Why melfs?

    The x-chapters (H+H) have some great data on resistor overload.

    MELFs dissipate more for a given footprint and can take a bigger solder
    fillet which holds them in place better under high vibration,
    particularly when the solder's weakened at high temperatures, and if
    potted, there's more body for the potting to hold.

    They're also much prettier.

    Personally, I find them easier to handle if I have to replace one
    because there's more to grip, but that's a trivial concern.

    But they have been noticeably harder to obtain for a few years.

    Q. Were MELFs originally made that way because they're essentially
    leaded parts without the leads? [It goes full circle - chop open a
    leaded dipped ceramic capacitor and you'll often find inside a surface
    mount part with leads soldered/welded on.]

    Yup. At one point some bright outfit was selling MELFs with square end
    caps to prevent them from rolling around. Dunno if they're still available.

    Cheers

    Phil Hobbs

    There are some diodes like that, thin end plates.

    Hard potting compounds sometimes expand as they cure, and cure
    non-uniformly. Imagine potting getting under such a melf and
    fracturing the skinny pin plating.

    https://www.apogeeweb.net/ModelImgs/BigIMG/J/JAN1N5811US.jpg

    Potting is bad news in general.



    --

    Anybody can count to one.

    - Robert Widlar

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to jlarkin@highlandsniptechnology.com on Fri Apr 29 11:30:50 2022
    jlarkin@highlandsniptechnology.com wrote:
    On Fri, 29 Apr 2022 10:17:17 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Clive Arthur wrote:
    <snip>
    Q. Were MELFs originally made that way because they're essentially
    leaded parts without the leads?  [It goes full circle - chop open a
    leaded dipped ceramic capacitor and you'll often find inside a surface
    mount part with leads soldered/welded on.]

    Yup. At one point some bright outfit was selling MELFs with square end
    caps to prevent them from rolling around. Dunno if they're still available. >>

    There are some diodes like that, thin end plates.

    Hard potting compounds sometimes expand as they cure, and cure
    non-uniformly. Imagine potting getting under such a melf and
    fracturing the skinny pin plating.

    https://www.apogeeweb.net/ModelImgs/BigIMG/J/JAN1N5811US.jpg

    Potting is bad news in general.

    "Doctor, Doctor, it hurts when I go like this!"
    "So don't go like that." ;)

    I don't recall seeing compounds that don't shrink at least a little.
    Having one expand might be pretty ugly. OTOH hard potting compounds can
    do things like crushing trimpots and electrolytics, so IIRC the wisdom
    is to pot the component side in a thin layer of soft, noncorrosive RTV
    before putting the epoxy on it.

    I've sometimes used conformal coatings, but never potting.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

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    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Clive Arthur@21:1/5 to jlarkin@highlandsniptechnology.com on Fri Apr 29 17:28:25 2022
    On 29/04/2022 15:38, jlarkin@highlandsniptechnology.com wrote:
    On Fri, 29 Apr 2022 10:17:17 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Clive Arthur wrote:
    On 25/04/2022 14:58, jlarkin@highlandsniptechnology.com wrote:
    On Fri, 22 Apr 2022 08:02:05 -0700 (PDT), "neo5...@gmail.com"
    <neo5bass@gmail.com> wrote:

    I suspect if a real source is around, no one wants to tell, but I am >>>>> having a hard time trying to get simple passive components. Melf
    resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    Thanks

    Don

    Why melfs?

    The x-chapters (H+H) have some great data on resistor overload.

    MELFs dissipate more for a given footprint and can take a bigger solder
    fillet which holds them in place better under high vibration,
    particularly when the solder's weakened at high temperatures, and if
    potted, there's more body for the potting to hold.

    They're also much prettier.

    Personally, I find them easier to handle if I have to replace one
    because there's more to grip, but that's a trivial concern.

    But they have been noticeably harder to obtain for a few years.

    Q. Were MELFs originally made that way because they're essentially
    leaded parts without the leads?  [It goes full circle - chop open a
    leaded dipped ceramic capacitor and you'll often find inside a surface
    mount part with leads soldered/welded on.]

    Yup. At one point some bright outfit was selling MELFs with square end
    caps to prevent them from rolling around. Dunno if they're still available. >>
    Cheers

    Phil Hobbs

    There are some diodes like that, thin end plates.

    Hard potting compounds sometimes expand as they cure, and cure
    non-uniformly. Imagine potting getting under such a melf and
    fracturing the skinny pin plating.

    https://www.apogeeweb.net/ModelImgs/BigIMG/J/JAN1N5811US.jpg

    Potting is bad news in general.

    It's horrible, but necessary in high shock/vibration equipment. We use
    RTV, as far as I know everyone does for high temperature high shock.

    [Actually, it's easier to clean a MELF populated board properly too,
    though that's a very marginal advantage as there will always be lots of 'ordinary' SM parts too.]

    --
    Cheers
    Clive

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    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to All on Fri Apr 29 09:58:45 2022
    On Thu, 28 Apr 2022 20:03:56 -0700 (PDT), whit3rd <whit3rd@gmail.com>
    wrote:

    On Tuesday, April 26, 2022 at 2:13:58 PM UTC-7, John Larkin wrote:
    On Tue, 26 Apr 2022 20:50:58 -0000 (UTC),
    DecadentLinux...@decadence.org wrote:

    Do you design with melfs? Why?

    They were to replicate the design and features of glass encapsulated,
    hermetically sealed components like diodes and such.

    Why?

    The glass package is thermally better than epoxies (or used to be)
    and extremely well sealed against contaminants. Classic diode test: run
    ten or twenty amps through a 1N4007 until you hear a 'pow' and see smoke. >Then put it on a curve tracer. It still works normally (underneath the epoxy,
    the package was plug-sealed glass). The epoxy is burnt and cracked, though.

    Do design with melfs?

    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

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  • From John Larkin@21:1/5 to clive@nowaytoday.co.uk on Fri Apr 29 10:00:23 2022
    On Fri, 29 Apr 2022 17:28:25 +0100, Clive Arthur
    <clive@nowaytoday.co.uk> wrote:

    On 29/04/2022 15:38, jlarkin@highlandsniptechnology.com wrote:
    On Fri, 29 Apr 2022 10:17:17 -0400, Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Clive Arthur wrote:
    On 25/04/2022 14:58, jlarkin@highlandsniptechnology.com wrote:
    On Fri, 22 Apr 2022 08:02:05 -0700 (PDT), "neo5...@gmail.com"
    <neo5bass@gmail.com> wrote:

    I suspect if a real source is around, no one wants to tell, but I am >>>>>> having a hard time trying to get simple passive components. Melf
    resistors, Pulse resistant resistors stuff like that.
    Are there any places selling basic components besides E-Bay?

    Thanks

    Don

    Why melfs?

    The x-chapters (H+H) have some great data on resistor overload.

    MELFs dissipate more for a given footprint and can take a bigger solder >>>> fillet which holds them in place better under high vibration,
    particularly when the solder's weakened at high temperatures, and if
    potted, there's more body for the potting to hold.

    They're also much prettier.

    Personally, I find them easier to handle if I have to replace one
    because there's more to grip, but that's a trivial concern.

    But they have been noticeably harder to obtain for a few years.

    Q. Were MELFs originally made that way because they're essentially
    leaded parts without the leads? [It goes full circle - chop open a
    leaded dipped ceramic capacitor and you'll often find inside a surface >>>> mount part with leads soldered/welded on.]

    Yup. At one point some bright outfit was selling MELFs with square end
    caps to prevent them from rolling around. Dunno if they're still available.

    Cheers

    Phil Hobbs

    There are some diodes like that, thin end plates.

    Hard potting compounds sometimes expand as they cure, and cure
    non-uniformly. Imagine potting getting under such a melf and
    fracturing the skinny pin plating.

    https://www.apogeeweb.net/ModelImgs/BigIMG/J/JAN1N5811US.jpg

    Potting is bad news in general.

    It's horrible, but necessary in high shock/vibration equipment. We use
    RTV, as far as I know everyone does for high temperature high shock.

    [Actually, it's easier to clean a MELF populated board properly too,
    though that's a very marginal advantage as there will always be lots of >'ordinary' SM parts too.]

    Melfs might be better for high voltage or pA circuits, because they
    probably clean better.

    --

    If a man will begin with certainties, he shall end with doubts,
    but if he will be content to begin with doubts he shall end in certainties. Francis Bacon

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